Cohasset students explore the harbor with Sea Perch

Tuesday

Oct 9, 2012 at 12:01 AMOct 9, 2012 at 9:20 AM

This summer 16 Cohasset High School students built and deployed Remotely Operated Vehicles (ROV’s) as part of the school’s Summer Institute program housed at CSCR, the Center for Student Coastal Research. The ROV’s, called Sea Perch, were used to explore and document eelgrass beds in Cohasset Harbor, the harbor channel, and around Whitehead. Recalled CHS senior Jack Thomae, “I had a blast. I did things I had never done before. It was a great feeling building it and seeing the motors turn on, and then using them to explore the eelgrass.”

Mary McGoldrick

This summer 16 Cohasset High School students built and deployed Remotely Operated Vehicles (ROV’s) as part of the school’s Summer Institute program housed at CSCR, the Center for Student Coastal Research. The ROV’s, called Sea Perch, were used to explore and document eelgrass beds in Cohasset Harbor, the harbor channel, and around Whitehead. Recalled CHS senior Jack Thomae, “I had a blast. I did things I had never done before. It was a great feeling building it and seeing the motors turn on, and then using them to explore the eelgrass.”

The Sea Perch project, funded by a grant from the Cohasset Education Foundation, allowed students to build the ROV from a commercial kit comprised of low-cost, easily accessible parts. The curriculum teaches basic engineering and science concepts with a marine engineering theme, but the student application of building the ROV to investigating critical marine habitat in Cohasset harbor made Cohasset’s Sea Perch project truly unique. US Army Corps of Engineers personnel underscored that point by informing the Sea Perch team via email that “your findings and data collection may be very helpful in determinations made by the Corps of Engineers as we prepare to dredge the Cohasset Federal Navigation Project in the coming years.”

Eelgrass beds play a critical role in marine ecosystems, contributing to water quality and species diversity. According to the Massachusetts Department of Fish, Game, and Wildlife, “Eelgrass meadows form the foundation for primary production and are very important to the coastal marine ecosystem. Loss of eelgrass habitat has been extensive in Massachusetts.”

Armed with this knowledge and with a 1994 engineer’s map of known eelgrass beds in Cohasset Harbor, the 16 students set out to complete the 3 phase Sea Perch project assembly phase, test phase, and habitat observation and exploration phase. “Student progress exceeded my expectations,” observed Jason McCabe, CHS English teacher and one of the project leaders. “It was a joy to see them build the kits from scratch, troubleshoot their individual and collective problems, and then use their own hand-built research tool to collaboratively investigate a real-world issue.”

Once the Sea Perches were fully assembled, students took them into Cohasset Harbor at low tide to gain experience and become proficient in maneuvering and operating the units. After tackling the issue of why certain units were more buoyant and therefore more mobile than others, the students collectively decided which Sea Perch ROV’s were the most reliable. These were the three ROV’s to which students attached GoPro cameras for phase three deployment and video documentation of eelgrass.

The first stage of the investigation phase brought students out to the inner side of the Bassing Beach jetty. Students worked in teams on shore and in the water in kayaks, a canoe, and a dory. Each team had a dedicated ROV driven by a student while others kept watch of the tether and recorded observations. Distances from the jetty to channel markers and buoys were established for reference points. Students quickly discovered that the greatest obstacle for underwater navigation was the lack of real-time video. In essence, the students were “driving blind.” To compensate, snorkel teams were assigned to each unit, which enabled student teams to produce very useful video footage inside the jetty, on the channel edge at Whale Meadow, and around the rocks at Whitehead.

Student results show very mixed reviews for harbor health. Whale Meadow and Whitehead reveal fairly healthy patches of eelgrass, but it’s a different story inside the jetty. From the navigational can marking the channel at the tip of the jetty to the mooring field, there's nothing but sand, silt, and very scarce patches of some wisps of vegetation other than eelgrass. Sea Perch video footage reveals a nearly barren harbor bottom, devoid of any healthy habitat.

Students reported these results to EPA and Army Corps officials who confirmed the “die-off” inside the jetty. Unknown to the Sea Perch team, an outbreak of wasting disease in the summer of 1995 infected dozens of acres of eelgrass beds throughout the south shore. Students discovered healthy patches of eelgrass, however, growing along the northern side of the channel from Whitehead to the navigational dolphin #12.

“It was a great experience,” said sophomore Hollis Hunnewell, “I’m looking forward to coming back next year to improve upon what we accomplished this summer. There’s so much more ground to cover. There’s got to be a way to rig these Sea Perch with wireless technology and video monitors. That’s our next challenge — building the bigger and better Sea Perch!”